1. Field of the Invention
The present invention relates to a control device of an industrial vehicle and an industrial vehicle loaded with this device, adapted to validate a parking brake (parking brake) automatically in the absence of an operator, thereby avoiding the danger of occurrence of an accident, and particularly relates to a control device of an industrial vehicle and an industrial vehicle loaded with this device, capable of reliably detecting operator absence, thereby preventing the malfunction of the control device.
2. Description of Related Art
Generally, in vehicles, including industrial vehicles, when the operator performing driving leaves his/her seat temporarily and leaves the vehicle, it is necessary for them to leave their seat while the vehicle is in a state in which a parking brake is locked in order to ensure safety.
However, when the operator has left his/her seat temporarily without stopping an engine or even in an engine stopped state, there is a danger that the vehicle may begin to move in an unmanned state if the parking brake does not work reliably or if the operator has forgotten to apply the parking brake. Therefore, vehicles including a safety device for avoiding this danger have been conventionally proposed.
For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-352152) discloses a safety device in which a seat switch which detects whether or not an operator is sitting on a driver's seat is provided, and the fact that the operator is away from the seat without applying the parking brake is detected by the seat switch to actuate a warning device.
As described above, when the operator has left his/her seat temporarily to leave the vehicle with an engine running or even in an engine stopped state, there is a danger that the vehicle will begin to move in an unmanned state if the operator has forgotten to apply the parking brake due to carelessness or the like.
Thus, the method of providing a seat switch in a seat portion of the vehicle and detecting operator absence to actuate the warning device becomes an effective safety measure. However, if the invention is applied to industrial vehicles represented by material handling machines, such as forklifts and reach stackers, or construction and civil engineering machines, such as motor graders, bulldozers, and wheel loaders, and if the warning device is a warning buzzer, there is a possibility that the operator will not be able to hear a noise when the warning buzzer is used in a noisy environment. Additionally, if the warning device is an alarm lamp or a warning sign, there is possibility that the operator will not notice if they are concentrating their attention on their work, and it cannot be definitively stated that safety is completely secured.
Additionally, techniques using the safety device interlocked with the seat switch have been variously suggested in the past. However, the industrial vehicles are often used in a work environment which is not organized, and the operator may bounce on his/her seat due to irregularities in the path being traveled. This may be erroneously detected as absence, and the safety device may malfunction. In particular, industrial vehicles often have a structure which does not include a suspension, and there is a danger that the malfunction of the safety device will manifest conspicuously.